1. Field of the Invention
The present invention relates to an umbilical-member processing structure for an industrial robot in which an umbilical-member connected to a work tool that is mounted on a distal end of a wrist, are disposed to run along the wrist via a tool managing and relaying device mounted on a forearm.
2. Description of Related Art
In general, as an industrial robot in which an umbilical-member connected to a work tool, are disposed to run along a wrist, a so-called umbilical-member-containing robot having the umbilical-member passed inside a hollow portion of the forearm and inside the wrist is disclosed in Japanese Patent Publication No. 2005-271003. In this case, in order to stabilize the behavior of the umbilical-member during the movement of the wrist axis, the umbilical-member may be sometimes passed inside a conduit. When the umbilical-member with relatively small diameter are subjected to bending or twisting due to movement of the wrist, it can absorb the bending or twisting with no adverse effect on its useful life. However, although a conduit can absorb bending, it cannot absorb twisting adequately, and therefore, it is necessary to provide a rotatable support member on either end of the conduit.
Although it is possible to provide a rotatable support member on the outer circumference of the conduit, there is a problem that the size of the wrist and the forearm needs to be increased in order to pass the conduit therethrough. On the other hand, if the rotatable support member is provided on the distal end of the conduit, the length of the conduit is increased accordingly, and the work tool or the work tool managing device has to be moved away in the extended direction. This has a disadvantage that the load imposed on the robot is increased and the interference with the peripheral equipments is more likely to happen.
In order to prevent excessive force from being exerted to the conduit, the rotatable support member may comprise rotation mechanism on both ends thereof. However, on the side of the work tool, it may be necessary to change the attitude of the work tool in accordance with the intended work, and there is a problem that, the farther the mounting position of the work tool becomes, the narrower and the more confined the range of possible attitude of the robot in the operating region becomes. That is, when the tool tip in the work tool is fixed and only attitude is changed, the farther the tool tip from the flange of the robot becomes, the larger the angle the basic axis of the robot has to move in order to take the same attitude becomes.